1. Technical Field
The present invention relates to a steering apparatus including a rack-and-pinion-type steering mechanism, and a detection means for detecting a steering torque applied to a steering member.
2. Description of Related Art
A steering apparatus to steer a vehicle is configured to drive a steering mechanism by transmitting a driver's operation of a steering member such as a steering wheel to the steering mechanism. For such a steering mechanism, a rack-and-pinion-type steering mechanism has been widely adopted. This type of steering mechanism is configured to convert a rotation of a pinion, in accordance with the rotational operation of the steering member, into an axial movement of a rack shaft having a rack meshed with the pinion, and perform a push-and-pull operation of right and left front wheels coupled to both ends of the rack shaft. The rack-and-pinion-type steering mechanism includes a support yoke resiliently contacting the rack shaft from both sides of a meshed portion between the rack and the pinion so that they favorably mesh with each other, without backlash, while applying preload to the meshed portion. Further, for many of the rack-and-pinion-type steering mechanisms, the pinion and the rack are formed with helical gears, each of which typically has a large contact ratio for mass load transmittance.
In recent years, in order to reduce the burden of the driver who operates the steering member, a steering apparatus configured as an electric power steering apparatus that detects a steering torque applied to the steering member by a torque sensor, drives a steering assist motor based on the detected steering torque, and applies an assisting force to the steering mechanism, is widespread.
The torque sensor is arranged at an intermediate position of the steering column which transmits the operation of the steering member to the steering mechanism, and is configured to detect a torsion generated on the steering column due to an action of the steering torque. Typically, to improve the detection accuracy of the steering torque by amplifying the torsion for the torque sensor, a coupling portion for coupling an input shaft on the side of the steering member and an output shaft on the side of the steering mechanism at an intermediate position of the steering column by a torsion bar of low rigidity is provided, and the torsion of the torsion bar in the coupling portion is detected by an appropriate means.